Struts2: Accessing a request Parameter from Action

[Abdul Mujeeb Md]

Hi,

I am using traditional Ajax and passing a hidden parameter to the Action, but when i try to retrieve this parameter value, it returns null.
What could be the reason for this?

Following code list the Ajax calling mechanism

  
createRequest();
		
document.forms[0].hdnLicenseNumber.value = document.forms[0].strLicenseNumber.value; // Value from Form Field
       	
var URL = "<%=strContextRoot%>addRecord_validateLicenseNumber.action"; // URL to be called

// Invoke the callback function
request.onreadystatechange = showMessage;

// Initiate the connection
request.open("GET", URL, true);

// Send the data
request.send(null);

When I try to retrieve the value for 'hdnLicenseNumber' it returns Null.

Thanks.

[Ankit Garg]

What you are trying to do will not work. The AJAX request will not take any form values in the request. You might add the request parameter in the request URL like

var URL = "<%=strContextRoot%>addRecord_validateLicenseNumber.action?hdnLicenseNumber="+document.forms[0].strLicenseNumber.value;

[Abdul Mujeeb Md]

Thanks Ankit,

This works.

[vikas sharmaa]

how to get the request sent by ajax call in the action class?

I have written the below code:

 
public class HelloWorld extends ActionSupport implements ServletRequestAware {
	
	HttpServletRequest request = null;
	
	public String execute() {
		
		System.out.println("inside execute");

		return "SUCCESS";
	}

	public void setServletRequest(HttpServletRequest httpServletRequest) {
		System.out.println("inside setServletRequest");
       this.request = httpServletRequest;
    }

}
 

but, on call of ajax function, nether setServletRequest nor execute method is getting called.

below is my ajax function in welcome.jsp file:

   
function show() {

	          alert('called');
	var xmlhttp;
	if (window.XMLHttpRequest)
	  {
	  // code for IE7+, Firefox, Chrome, Opera, Safari
	  xmlhttp=new XMLHttpRequest();
	  }
	else if (window.ActiveXObject)
	  {
	  // code for IE6, IE5
	  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
	  }
	else
	  {
	  alert("Your browser does not support XMLHTTP!");
	  }
	
	
		var URL = "http://localhost:8080/Simple/HelloWorld.action?name=vikas"; // URL to be called  
	  
	// Invoke the callback function  
	request.onreadystatechange = showMessage;
	  
	// Initiate the connection  
	request.open("GET", URL, true);  
	  
	// Send the data  
	request.send(null);
}

function showMessage() {
	if(xmlhttp.readyState==4)
	  {
	  document.myForm.time.value=xmlhttp.responseText;
	  }
}

please let me know, where i am going wrong. thank you

[Abdul Mujeeb Md]

Hi,

Try to get the request Object this way:

String strNameFromAjaxRequest = getParameterValue("name");

Add this code in your Action.

Map parameters = null;

public final Map getParameters() {
        parameters=ActionContext.getContext().getParameters();
        return parameters;
	}

public String getParameterValue(String param){
		Object paramObj = getParameters().get(param);
		if(paramObj == null) return null;
		return ((String[])paramObj)[0];
	}

Hope this works

[David Newton]

You haven't included any configuration information, so it's impossible to help.

Are you really not using a JavaScript library to handle the Ajax stuff? It's sooooo much easier and cleaner.

[Abdul Mujeeb Md]

David,

I haven't explored on it yet. Will catch on it soon.

[vikas sharmaa]

Newton,

i am not using any JavaScript library to handle the Ajax stuff. i just follow w3school site tutorial. please help me.

Abdul Mujeeb Md wrote:
Try to get the request Object this way:

String strNameFromAjaxRequest = getParameterValue("name");

i can try it. but first either setServletRequest or execute method should get call. in my case, action class is not getting called on sending request from the ajax method.

please help.

[David Newton]

David Newton wrote:You haven't included any configuration information, so it's impossible to help.

[vikas sharmaa]

hi newton,

please find below my configuration files:

struts.xml

 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
	<package name="default" extends="struts-default">

		<action name="HelloWorld" class="com.HelloWorld">
			<result name="SUCCESS">/welcome.jsp</result>
		</action>
	</package>
</struts>
   

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
	<display-name>Simple</display-name>
	
	<filter>
		<filter-name>struts2</filter-name>
		<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
	</filter>
	
	<filter-mapping>
		<filter-name>struts2</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
</web-app>

[vikas sharmaa]

newton,

had i provided all the required configuration infos? or something is missing. please tell me.

[David Newton]

And the app context is "Simple"? If so, it's not immediately obvious to me what's wrong.

Try using the config-browser plugin to see what S2 thinks your configuration is, and turn up logging to see if there are any startup issues or errors during the request processing.

[vikas sharmaa]

on the tomcat console, below warning is coming:

WARNING: No configuration found for the specified action: 'HelloWorld.action' in
namespace: '/'. Form action defaulting to 'action' attribute's literal value.

but my HelloWorld action class is called and return SUCCESS. then opening welcome.jsp page. HelloWorld action class is not getting called from ajax function only.

if ajax is not able to call the action class because of above warning then how could i fix this warning.